Up until 1968, the United States government had a Top Secret plan for what to do in the event that the president died or went missing under mysterious circumstances. The plan was: Nuke the shit out of everyone right now.

The plan, code-named "Furtherance," was revealed today for the first time by the National Security Archive, a project affiliated with George Washington University that seeks declassification and publication of historical documents. The archive obtained a series of White House documents from 1968 that record President Lyndon Johnson's deliberations about altering Furtherance, which at the time mandated an automatic "full nuclear response against both the Soviet Union and China" if the president was killed in an attack, or couldn't be found. That's both China and the Soviet Union, without any evidence that either was involved in the attack. Just to be safe!

There have been instructions on authority to release nuclear weapons in the event the President has been killed or cannot be found. This is to prevent a breakdown in the chain of command...

We recommend three major changes:

(1) Under the former orders a full nuclear response against both the Soviet Union and China was ordered if we were attacked. Under the change, the response could go to either country—not both. There could be small-scale or accidental attack. We do not recommend full attack at all times. This would permit a limited response.

Thankfully, Johnson followed the recommendations of his advisors—one Marine Corps commandant general argued that it was "unfair" to nuke China if the Soviets attacked us—and altered the policy accordingly to make sure we didn't visit a nuclear holocaust on two countries if the president slipped his security detail for a few hours and no one could find him.